Cytogenetic and genetic data support Crossodactylus aeneus Müller, 1924 as a new junior synonym of C. gaudichaudii Duméril and Bibron, 1841 (Amphibia, Anura).

Stenio Eder Vittorazzi,Luciana Bolsoni Lourenço,Luiz Norberto Weber,Daniel Pacheco Bruschi,Shirlei Maria Recco-Pimentel,Michelle Louise Zattera

doi:10.1590/1678-4685-gmb-2020-0301

Abstract

The nominal anuran species Crossodactylus gaudichaudii Duméril and Bibron, 1841 and Crossodactylus aeneus Müller, 1924 are indistinguishable based on adult and larval morphology, being subject of taxonomic doubts. Here, we describe the karyotypes of C. gaudichaudii and C. aeneus, using classical and molecular cytogenetic markers. In addition, we used sequences of the H1 mitochondrial DNA to infer their phylogenetic relationships by Maximum Likelihood (ML) and Maximum Parsimony (MP) approaches and species delimitation test (by bPTP approach). The karyotypic data do not differentiate C. gaudichaudii and C. aeneus in any of the chromosome markers assessed. In both phylogenetic analyses, C. gaudichaudii and C. aeneus were recovered into a strongly supported clade. The species delimitation analysis recovered the specimens assigned to C. gaudichaudii and C. aeneus as a single taxonomic unit. Taken the cytogenetic and genetic results together with previous studies of internal and external morphology of tadpoles and biacoustic pattern, C. gaudichaudii and C. aeneus could not be differentiated, which supports the hypothesis that they correspond to the same taxonomic unit, with C. aeneus being a junior synonym of C. gaudichaudii.

Highlights

The genus Crossodactylus (Hylodidae) includes 14 species of diurnal frogs that inhabit streams banks, ranging from Alagoas state in northeastern Brazil to Rio Grande do Sul state in southern Brazil, and being found in southern Paraguay and northern Argentina (Carcerelli and Caramaschi, 1993; Frost, 2020)
The species C. werneri, C. trachystomus, C. caramaschii and C. schmidti formed the sister-group of a clade composed of C. gaudichaudii and C. aeneus, with low bootstrap support (Figure 2 and Figure S1)
Chromosomal analysis of C. gaudichaudii and C. aeneus showed the same diploid (2n) and fundamental (FN) numbers previously reported to C. caramaschii (Aguiar-Jr et al, 2004; Amaro, 2005), C. dispar (De Lucca et al, 1974), C. grandis (Beçak, 1968) and C. schmidti (Amaro, 2005), suggesting an overall similarity among the Crossodactylus karyotypes

Summary

Introduction

The genus Crossodactylus (Hylodidae) includes 14 species of diurnal frogs that inhabit streams banks, ranging from Alagoas state in northeastern Brazil to Rio Grande do Sul state in southern Brazil, and being found in southern Paraguay and northern Argentina (Carcerelli and Caramaschi, 1993; Frost, 2020). The taxonomic investigation of the Crossodactylus species has been based on phenotypic features, that is, the external and internal morphology of adults and larvae, bioacoustics, and morphometric parameters (Caramaschi and Sazima, 1985; Pimenta et al, 2014; 2015). Species of Crossodactylus were included in some molecular phylogenetic inferences (e.g., Pyron and Wiens, 2011; Grant et al, 2017), a phylogenetic analysis focused on this genus remain to be done. Pimenta et al (2014) questioned the validity of the analysis of morphometric characters in this genus, given that many characters overlap extensively between species (except in Crossodactylus grandis). Because of the phenotypic similarities of the Crossodactylus species, more reliable and conclusive taxonomic studies will require the systematic integration of morphological and molecular evidence

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